"Vayeitsei Yaakov meBe'er Sheva vayelech Charana"
Rashi comments, quoting Chazal, that the Torah, seemingly gratuitously, accentuates Yaakov's leaving Be'er Sheva to teach an important lesson. When a Yaakov leaves a city, the splendor, radiance, and glory of the city also depart.
Why does the Torah frame this important lesson negatively? Why not depict the luster of the tzaddik by teaching that when a tzaddik arrives in a city it becomes filled with splendor, radiance, and glory?
The answer to these questions highlights a tragic human tendency. Of course, when a tzaddik arrives, his arrival and continued presence bring splendor, radiance, and glory. But we tend not to appreciate that wonderful beracha - at any rate, not fully appreciate it. Only when vayeitsei Yaakov, when the tzaddik leaves, does one fully realize what he had. It is tragic to first fully realize what one had after losing it. If only one had appreciated the tzaddik while he was living locally, one could have benefited so much more - seek him out, learn from him, get close to him, etc. When appreciation is retrospective, none of this is possible.
The lesson is clear. We must make a concerted effort to appreciate the berachos the Rebbono Shel Olam bestows upon us while we have them and can take full advantage. The berachos of Hakadosh Baruch Hu are endless - tzaddikim in our midst, family, health, parnassa, etc. We need to step back and appreciate in order to feel gratitude and in order to take full advantage.